The present invention relates to techniques for producing the perception of control over movement of an object within a three-dimensional workspace presented on a display.
Bier, E. A. and Stone, M. C., "Snap-Dragging," Computer Graphics, Vol. 20, No. 4, 1986, pp. 233-240, describe snap-dragging, a technique that helps a user to place points with precision using an interactive drawing system. As described in Section 1, snap-dragging is based on the idea of snapping the display cursor to points and curves using a gravity function. Section 2 describes snap-dragging in detail, mentioning at page 233 that transformed objects are smoothly dragged into position. The user specifies which region and which kinds of alignment objects are of interest, and the system automatically constructs alignment objects of that kind in the region. The alignment objects are visible when a user is moving an object. Section 4.3, discussing performance, mentions that an object affected by a transformation must move smoothly as it is dragged into position, which can be solved by reducing detail during dragging or rendering moving objects into a bitmap that is repeatedly repositioned. The last paragraph on page 239 discusses editing objects in three dimensions.
Bier, E. A., "Skitters and Jacks: Interactive 3D Positioning Tools," Proceedings, 1986 Workshop on Interactive 3D Graphics, Oct. 23-24, 1986, ACM, New York, 1987, pp. 183-196, describes interactive techniques for scene composition, the precise placement of scene objects relative to each other using affine transformations. Section 2 describes smooth object motion in which objects move through intermediate configurations in real time until they reach their final destinations. Section 2.4 indicates that smoothness is useful for obtaining an aesthetically pleasing relationship between objects and to give the user confidence. Section 4.1 describes how skitters move when the user moves a two dimensional cursor around the screen, and appear on the surface of an object, as illustrated in FIG. 1. Section 4.5 further describes how a skitter can be moved using a mouse. Section 5.3 describes smooth motion transformations parallel to the viewing plane or parallel to a PlaneSelection plane. Also, an object can be attached to a skitter which can then be moved normally.